Corsair twinx XL not cutting it

I'm OCing the rig in my sig and I hit a wall with my RAM. no matter the timming or voltage fed to it it will not go over 250 mhz, I know my CPU did go to 270mhz on my friends rig and that's where his ram gave out. I need to know what is the best ram that will give me beast performence and speed for a rig like my current XL one...and I am not on a budget so anything that is not overpriced for the given performence is fine by me

the samsung tccd used in the hi speed ddr1 (pc4400/pc4800) is about the best for an a64 setup i hear. especially on a 754 pinout in single channel. alot of guys are getting 300+ with the dfi lanparty.

Trouble is I got a neo2 939 dual channel setup...but I'll look into it anyway, you never know